Government is coercion. It's the single biggest characteristic of any government anywhere around the world. They only differ in the extent of coercion that they impose upon their citizens.
Absolute monarchies for instance are absolute dictatorships. Zero election, zero transfer of political power outside of the clan, zero to minimal political dissent and opposition. There are dozens of control measures to ensure such absolute dictatorship.
Democratic governments tolerate political opposition and transfer of power outside of a political clan via regular elections. But since almost all democratic governments are BIG and the bureaucracies are expansive, the coercion to sustain them -- high and multiple taxes and fees -- is also high.
The bigger the extent of coercion, the bigger the political dissent by the citizens, even if kept in private. Dictators and government leaders know this. In addition, there are also conflict among BIG governments themselves like territorial disputes. Thus, they need to keep huge police forces, army, navy, air force and armed units. And they give them lots of guns, bombs, tanks, battle ships, fighter jets and choppers, radars and communication equipment, and other hardwares.
Below is a nice chart by The Economist, Present Arms, March 23rd 2011 issue. Their primary source of data is the Stockholm International Peace Research Institute (SIPRI).
The US, Russia and Germany supplied 64 percent of all arms importation by all countries around the world from 2006-2010. Manufacturing and selling guns, ammunitions and bombs is one huge business. It is a highly sustainable business.
All dictators, monarchs, kings, emirs, sultans, prime ministers and presidents always want to show their huge stockpile of arms, bombs, missiles, tanks and other war paraphernalia during national day or independence day parades. A wide phalanx of police and military generals, colonels, admirals and other officers are clapping and smiling at the huge amount of weapons of death and destruction, carried and operated by the men and women trained to kill and destroy, under their commands.
When wars erupt between countries or within a country (ie, a civil war), the immediate target for destruction and demolition by their respective soldiers are the military targets of the enemy. Whoever wins, or if a stalemate results, each warring country will need to re-arm again and prepare for another round of war, actual or imagined. And that's how the arms exporting countries and their businesses make tons of money.
Huge arms expenditures and BIG governments, they go hand in hand. Always.
(See also my recent and related paper, European conflict in the Libyan conflict,